Send events to JavaScript

module

ticker.lucent.ts

import { delay } from "lucent:core";

const running = new Set<number>();
let nextId = 1;

/** Calls `onTick` every `ms` milliseconds, until `stop(id)`. */
export async function start(ms: number, onTick: (count: number) => void): Promise<number> {
  const id = nextId++;
  running.add(id);
  void tick(id, ms, onTick);
  return id;
}

async function tick(id: number, ms: number, onTick: (count: number) => void): Promise<void> {
  let count = 0;
  while (running.has(id)) {
    await delay(ms);
    if (running.has(id)) onTick(++count);
  }
}

export function stop(id: number): void {
  running.delete(id);
}

JS usage

Clock.tsx

import { useEffect, useState } from "react";
import { Text } from "react-native";
import { start, stop } from "./src/ticker.lucent";

export function Clock() {
  const [count, setCount] = useState(0);
  useEffect(() => {
    const started = start(1000, setCount);
    return () => void started.then(stop);
  }, []);
  return <Text>{count}</Text>;
}

• JavaScript passes a function, and Lucent keeps it while tick runs. Each call from async code is posted to the JS thread.
• start returns an id and stop takes it back. Stopping is what lets go of the function.
• An event handler called from async code must return void or a Promise.

For events that come from the SDK, keep the delegate or listener in a Map by id instead of the Set. Implement a delegate or listener shows one, and the network state example the whole pattern.